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Cold Start runs badly for 5 mins then smooths out and runs fine
Hello All,
I have a 91, 500SL that starts right up, then idles very rough for about a minute. For the next 3 - 4 mins. it won't take fuel. If I step on the gas (easy, gradually, hard or stomp it) it will bog, sometimes misfire through the carb and shutoff. If I just leave it alone for 3 - 5 mins after starting it, it runs like a top. If I shut it off and go to restart it while it's, even fairly warm, it starts and runs fine. I've replaced plugs, wires, caps & rotors. My mechanic (who's about to slit his throat or mine) has chased down every vacuum line below the intake and the fuel distributor. I'm up for any and all suggestions????? Thanks! Ready to go to the paint shop!
It seems to me the fuel mixture is too lean after a cold start. There is a simple way to check.
Locate the round diagnostic socket on the inner fender by the ABS/ASR control unit. When the engine is at operating temperature and idle, measure the DC voltage between sockets #2 and #3 of the connector. It should fluctuate slightly and average 4-9 volts, but if the mixture is lean the voltage will be 10 volts or more.
I printed your info and gave it to my, current, mechanic. Unfortunately he, no longer had ODB1 capabilities, so he's flying a little blind. My wrench of decades finally retired after the 5th heart attack (slacker) and so I'm in the market for a good 129 guru. If anyone has any recommendations in the South Jersey area, I'm all ears??? Thanks a bundle and I'll let you know if he can sort this out.
I printed your info and gave it to my, current, mechanic. Unfortunately he, no longer had ODB1 capabilities, so he's flying a little blind. My wrench of decades finally retired after the 5th heart attack (slacker) and so I'm in the market for a good 129 guru. If anyone has any recommendations in the South Jersey area, I'm all ears??? Thanks a bundle and I'll let you know if he can sort this out.
It sounds like no scanner required... just a volt meter.
To: All,
Thank you for all of for your replies. As it ended up, it was one of the computers under the hood on the passengers side. I, wisely, bought a parts car (that also had a nice set of Lorinser D93's on it) and with the help of Ditmire's in Pleasantville, NJ, they diagnosed it. I supplied it and it was an instant fix! These folks are cheap and they aren't real fast, but they are real good and I recommend them to anyone with a star on the hood (particularly older iron).
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Computer Issues
